Melih Birhan KENANOĞLU, Mohammad AHMADI-ADLI, Nabi Kartal TOKER, Nejan HUVAJ

Effect of Unsaturated Soil Properties on the Intensity-Duration Threshold for Rainfall Triggered Landslides

Rainfall triggered landslides are one of the most common natural hazards in many countries all around the world, as well as in Turkey. This study investigates the effect of unsaturated soil properties on landslide-triggering rainfall intensity-duration threshold. In addition to the time to failure, the suction (negative pore water pressure) distribution in the slope, the shape and depth of the failure surface are also evaluated. Properties of soil-water characteristic curve which affect the distribution of suction in the soil in response to changes in water content are varied in a parametric study. Effects of air entry value (relates to particle size), de-saturation rate (relates to uniformity of particle size distribution), saturated volumetric water content (relates to void ratio) and residual volumetric water content (relates to fines content and characteristics) are evaluated by determining the intensity-duration threshold numerically by carrying out infiltration and slope stability calculations. The variation of unsaturated soil properties is found to significantly alter the landslide mechanism (ranging from mere surface erosion to groundwater level rise in response to complete infiltration) and consequent intensity-duration thresholds for the same slope geometry. Among the parameters considered, air entry value appears to be the most influential parameter. The effects of the slope angle and initial moisture condition on threshold rainfall intensity-duration are also investigated. This study could be useful for creating the basis and mechanical understanding for future research on early warning systems.

Anahtar Kelimeler:

Unsaturated soil, rainfall triggered landslide, intensity-duration threshold, soil water characteristic curve, suction

Effect of Unsaturated Soil Properties on the Intensity-Duration Threshold for Rainfall Triggered Landslides

Keywords:

rainfall triggered landslide, intensity-duration threshold, soil water characteristic function, suction,

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Ahmadi-adli, M., Huvaj, N., and Toker, N. K.: Rainfall Triggered Landslides in Unsaturated Soils: A numerical sensitivity analysis, in Proceedings of 10th International Congress on Advances in Civil Engineering, Middle East Technical University, Ankara, Turkey, 17-19 October 2012, Article 1179, 2012.
Ahmadi-adli, Mohammad (2014), Shallow Landslides Triggered By Rainfall In Unsaturated Soils, Phd Thesis, Middle East Technical University
Ahmadi-adli, M, Huvaj, N. And Toker, N.K. (2014) Prediction of seepage and slope stability in a flume test and an experimental field case, Procedia Earth and Planetary Science, v.9, p.189-194 (doi: 10.1016/j.proeps.2014.06.022)
Aleotti, P.: A warning system for rainfall-induced shallow failures, Eng. Geol., 73, 247-265, 2004.
Alonso, E., Gens, A., and Delahaye, C.: Influence of rainfall on the deformation and stability of a slope in over consolidated clays: a case study, Hydrogeology Journal, 11(1), 174-192, 2003.
Brunetti, M. T., Peruccacci, S., Rossi, M., Luciani, S., Valigi, D., and Guzzetti, F.: Rainfall thresholds for the possible occurrence of landslides in Italy, Nat. Hazards Earth Syst. Sci., 10, 447-458, 2010.
Caine, N.: The rainfall intensity-duration control of shallow landslides and debris flows, Geogr. Ann., 62 A(1-2), 23-27, 1980.
Chen, H., Dadson, S., and Chi, Y.: Recent rainfall induced landslides and debris flow in northern Taiwan, Geomorphology, 77, 112-125, 2006.
Corominas, J.: Landslides and climate, in: Proceedings of the 8th International Symposium on Landslides, edited by: Bromhead, E., Dixon, N., and Ibsen, M. L., A. A. Balkema, Cardiff, 4, 1–33, 2000.
Crosta, G. B., and Frattini, P.: Distributed modelling of shallow landslides triggered by intense rainfall, Nat. Hazards Earth Syst. Sci., 3, 81-93, doi:10.5194/nhess-3-81-2003, 2003.
Eichenberger, J., Ferrari, A., and Laloui, L.: Early warning thresholds for partially saturated slopes in volcanic ashes, Computers and Geotechnics, 49, 79-89, 2013.
Gallage, C. P. K., and Uchimura, T. (2010). Investigation on parameters used in warning systems for rain-induced embankment instability. In Kwok, Charles (Ed.) Proceedings from the 63rd Canadian Geotechnical Conference (GEO2010), GEO2010 Calgary, Calgary, Alberta, 1025-1031.
GEO-SLOPE. (2007). SEEP/W, GEO-SLOPE International Ltd., Calgary, Alberta, Canada.
Guzzetti, F., Peruccacci, S., Rossi M., and Stark, C.P.: Rainfall thresholds for the initiation of landslides in central and southern Europe, Report, Istituto di Ricerca per la Protezione Idrogeologica, Perugia, Italy, 48 pp., 2007.
Guzzetti, F., Peruccacci, S., Rossi M., and Stark, C.P.: The rainfall intensity–duration control of shallow landslides and debris flows: an update, Landslides, 5, 3-17, 2008.
Iverson, R.M.: Landslide triggering by rain infiltration, Water Resources Research, 36(7), 1897-1910, 2000.
Lu, N., and Godt, J.W.: Hillslope Hydrology and Stability, Cambridge University Press, Cambridge, UK, 2013.
Lu, N., and Likos, W.J.: Unsaturated Soil Mechanics, John Wiley & Sons, NJ, 2004.
Montgomery, D.R., and Dietrich, W.E.: A physically based model for the topographic control of shallow landsliding, Water Resources Research, 30(4), 1153–1171, 1994.
Morgenstern, N.R., and Price, V.E. (1965). The Analsis of the Stability of General Slip Surfaces. Geotechnique, Vol. 15, pp. 79-93.
Naval Facilities Engineering Command (NAVFAC). (1986). Design Manual - 7.1 p 7.1 - 149
Reichenbach, P., Cardinali, M., De Vita, P., and Guzzetti, F.: Regional hydrological thresholds for landslides and floods in the Tiber River Basin (central Italy), Environmental Geology, 35(2&3), 146-159, 1998.
Vanapalli, S.K., Fredlund, D.G., Pufahl, D.E., and Clifton, A.W. (1996)."Model for the prediction of shear strength with respect to soil suction". Canadian Geotechnical Journal, 33(3), 379-392.
Wilson, R.C., and Wieczorek, G.F.: Rainfall thresholds for the initiation of debris flow at La Honda, California, Environ. Eng. Geosci., 1(1), 11–27, 1995.
Wu, W., and Sidle, R.C.: A distributed slope stability model for steep forested basins, Water Resour. Res., 31, 2097–2110, 1995.